Self-cleaning oven latch-lock-control arrangement

ABSTRACT

A latch-lock-control arrangement in which a control and locking mechanism is located at the rear of the oven and in which the linking means between the rear mechanism and the door latching means at the front of the oven is arranged to accommodate various oven sizes and manufacturing tolerance conditions by having the box in which the locking and control components are mounted being yieldable and both a linking bar and a stabilizer bar are provided with a number of attachment locations. The control mechanism also includes overheat safety switch means responsive to over temperatures both in excess of cooking temperatures and cleaning temperatures, and a mechanism for recalibrating the safety switch means in accordance with latching of the oven door for a cleaning cycle.

[451 Oct. 14,1975

[ SELF-CLEANING OVEN LATCH-LOCK-CONTROL ARRANGEMENT [75] Inventor: Clarence G. Phifer, Columbia, SC.

[73] Assignee: White-Westinghouse Corporation, Cleveland, Ohio [22] Filed: Dec. 24, 1974 [21] Appl. No.: 536,057

[52] US. Cl. 219/413; 126/197; 219/398 [51] Int. Cl. F27D 11/02 [58] Field of Search 219/393, 398, 410, 411,

[56] References Cited UNITED STATES PATENTS 3,317,708 5/1967 Bowling 219/412 3,387,874 6/1968 Holtkamp.... 292/201 3,390,909 7/1968 Nagel 292/201 3,410,988 ll/1968 Nagel... 219/412 3,638,638 2/1972 Phifer 126/197 3,639,726 2/1972 l-loltkamp 219/413 3,648,011 3/1972 Holtkamp 219/413 Primary Examiner-Nolodymyr Y. Mayewsky Attorney, Agent, or FirmMcNenny, Farrington, Pearne & Gordon [5 7] ABSTRACT A latch-lock-control arrangement in which a control and locking mechanism is located at the rear of the oven and in which the linking means between the rear mechanism and the door latching means at the front of the oven is arranged to accommodate various oven sizes and manufacturing tolerance conditions by having the box in which the locking and control components are mounted being yieldable and both a linking bar and a stabilizer bar are provided with a number of attachment locations. The control mechanism also includes overheat safety switch means responsive to over temperatures both in excess of cooking temperatures and cleaning temperatures, and a mechanism for recalibrating the safety switch means in accordance with latching of the oven door for a cleaning cycle.

4 Claims, 8 Drawing Figures US. Patent Oct. 14,1975 v Sheet 1 of3 3,912,904

FIG.4.

33 32 28 DCBA 1 Eh; o o 5 o Sheet 2 of 3 391290 U.S. Patent Oct. 14, 1975 US. Patent Oct.14,1975 SheetB 0f3 3,912,904

SELF-CLEANING OVEN LATCH-LOCK-CONTROL ARRANGEMENT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to the art of self-cleaning oven door locking and control arrangements.

2. Description of the Prior Art An arrangement in which the motion of latching a door at the front of the oven is transmitted to a locking and control box at the rear of the oven is disclosed in U.S. Pat. Nos. 3,387,874; 3,390,909 and 3,410,988. An arrangement in which a safety switch for both cooking and cleaning overheat is recalibrated in accordance with latching of the oven door, but in which the control arrangement is located at the forward portion of the oven, is disclosed in U.S. Pat. Nos. 3,638,638 and 3,639,726.

The arrangement according to my invention is considered to be an improvement in a number of respects over those arrangements.

SUMMARY OF THE INVENTION In accordance with my invention the locking and control mechanism is located generally at the rear of the oven and is linked to the means for latching the door at the front of the oven by a linking bar and a stabilizer bar, the linkiing bar being movable forwardly in accordance with turning of a bell crank and being adapted to thereby draw a draw bar of the control box forwardly, and a stabilizer bar is connected at its front to the pivot point of the bell crank and at its rear to a location on the box. Both the linking bar and stabilizer bar have a number of front-to-rear spaced attachment locations for connection to the draw bar and box, respectively, with successively forward stabilizer bar attachment locations being selected to correspond with successively rearward draw bar attachment locations.

The control box also carries bimetal means responsive to reflect oven temperature and for operating the safety switch means under overheat conditions. The bimetal means include both a main bimetal and a lag compensating bimetal which project forwardly from the lock box and are carried by structure which is yieldably biased toward the oven liner.

Other features of my invention considered subsidiary to the foregoing will be outlined in the following.

DRAWING DESCRIPTION FIG. 2 is a fragmentary, horizontal sectional view corresponding to one taken along the line II-II of FIG. 1 and illustrating the latching means'and the forward part of the link means in an unlatched position;

FIG. 3 is a top view of the latching means similar to FIG. 2illustrating the relationship of parts when the latching means is in a latched position;

FIG. 4 is a fragmentary, horizontal'sectional view corresponding to one taken along the line IVIV of FIG. 1, showing the rear of the linkage and the top of the control box;

FIG. 5 is a partlybroken isometric view of the arrangement by which the bimetal sensor assembly is secured to the control box to be biased downwardly and yieldably upwardly;

FIG. 6 is a rear elevational view of the control box in an unlocked condition; y

FIG. 7 is a sectional view corresponding to one taken along the line VIIVII of FIG. 6 and illustrating parts of the safety switch means and its operating lever; and

FIG. 8 is a partly broken side elevational view of the lock box with its bimetal mechanism in its initially biased position relative to a rear part of the oven liner on which it will seat in the assembled relationship.

DESCRIPTION OF THE PREFERRED EMBODIMENT Range and Oven Structure (FIG. 1)

The following description will generally correspond with that of U.S. Pat. Nos. 3,390,909 except as to the precise location of the rear locking and control box 2, which is elevated as compared to the location disclosed in the noted patent. The range includes an outer housing 4 supporting a cook top 6 and controlpanel 8. The forwardly open oven cavity is defined by a liner 10 which contains top and bottom heating elements 12 as well as thermostatic means 14 and is closed by a door 16 hinged along its lower edge. An operable handle 18 near the top of the door is rotatable to turn a bolt 20 up out of the top edge of the door into a slot in the keeper plate 22 carried by the oven framing structure.

Latch and Keeper Assembly Linking Means (FIG. 2-4) Some of the parts to be described are common to those in U.S. Pat. No. 3,390,909 and so will not be described in detail. The keeper plate 22 has a slot 23 therein up into which the bolt 20 moves as the handle 18 is turned. A bell crank 24 has one arm 25 and another arm 26, the crank being pivotally mounted to the plate at 27. When the handle 18 is turned to a latched position the bolt 20 is turned up into the slot to latch the door and in moving through the slot engages arm 25 and accordingly rotates the bell crank in a counterclockwise direction which draws the other arm 26 for- 'wardly.

A linking bar 28 has its forward end connected to the arm 26 and a stabilizer bar 30 has its forward end connected at the pivot location 27 of the bell crank. The rear end of the linking means is connected to a draw bar 32 which projects forwardly out of the box 2 (FIG.

4). The draw bar has a series of holes spaced apart in a front-to-rear direction which are indicated by the alphabetical notations D, C, B, A. The rear of the linking bar has a turned downtab 33 with a small hole therein. The connection between the linking bar and draw bar is made, after locating the tab at a selected hole in the draw bar, with a hairpin-shaped pin 34 which has one leg passing above the bar and through the hole in the tab, and the other leg passing underneath the draw bar. The width of the tab corresponds closely to the diameter of the holes in the draw bar so that front-to-back play is substantially avoided. This arrangement also reduces the chance of binding and avoids the problems due to vertical or horizontal or axial misalignment of the linking bar and draw bar.

The stabilizer bar also has a series of front-to-rear spaced attachment locations in the form of holes identified' by the letters A, B, C, D. It will be noted that the succession of these holes is reversed with respect to the succession of holes in the draw bar. The attachment location on the box is a stud 36. The attachments of the linking bar and stabilizing bar to their connecting parts are made by placing the tab of the linking bar at a draw bar hole which corresponds alphabetically with a hole in the stabilizer bar. For example, if the tab is placed at hole C of the draw bar, the hole C of the stabilizing bar is placed on the stud of the lock box. Thus the relationship is that successively forward holes of the draw bar correspond to successively rearward holes in the stabilizing bar. This arrangement provides benefits of reduced assembly time, the use of standard linking and stabilizer bars for different types of ovens (for example, built-in and free-standing), and accommodates manufacturing tolerances of different distances from the front to the rear of ranges of a given model. Also, as will be explained hereinafter, the lock box can be tilted from the vertical in one direction or another without deterimental effect to take care of manufacturing tolerances.

It is noted that the stabilizer bar has the same purpose as that described in U.S. Pat. No. 3,399,909; that is, to compensate for the thermal expansion and contraction of the range frame.

Lock and Control Box (FIGS. 5-8) The box 2 carries the draw bar 32 with its depending leg 37 carrying a snap-cricket type lever 38 which moves a pivot arm assembly 39 operable to reset a normally closed safetyswitch 40 for a self-cleaning operation when the draw bar 32 is moved forwardly. The switch 40 is calibrated so that when it is not reset it will open if the oven temperature should exceed a safe cooking temperature of say 600F. (316C.) during a cooking operation. The switch is reset when the user latches the door so that then it will open in response to a temperature in excess of a safe self-cleaning temperature, such as say 1 100F. to 1300F. (593C. to 704C) The opening of the safety switch 40 is effected through movement of a main bimetal 42 (FIG. 8) and a compensating bimetal 44 which are coupled and carried in a structure 46. The structure 46 projects forwardly from the lock box, is channel-shaped in cross section, and is downwardly open. The forward end of the main bimetal 42 is thermally isolated from the channel 46 by a pair of ceramic spacers 47 but is mechanically attached through the spacers to a side wall of the channel. A heat isolating block 48 mechanically couples the adjacent ends of the main and compensating bimetals. The right end of the compensating bimetal, as viewed in FIG. 8, will move toward the viewer as the oven temperature increases. This right end of the bimetal 44 is the edge of the bimetal facing the viewer in FIG. 6.

A safety switch pivot arm 50 (FIG. 6) can pivot clockwise as indicated by the arrow and has a toe 51 which is adapted to be engaged by the bimetal 44. As the bimetal pushes the toe 51 to the left as indicated by the arrow, the arm 50 rotates and its face 52 will move leaf 53 carrying one of the contacts of the safety switch 40 toward a position away from the other contact of the safety switch 40. If the switch 40 has been reset for a cleaning operation, the leaf 53 will have to move substantially farther to break the contact.

The pivoting of the safety switch pivot arm 50 is coupled through a hairpin type spring 54 to a locking lever 56 pivotally mounted on the same axis as the switch pivot arm 50. The lever has an extended upper length 58 adapted to move to the right in the direction as indicated by the arrow in FIG. 6 to take a position behind the depending leg 37 ofthe draw bar when the draw bar is moved forwardly by latching of the oven door. It is noted that the safety switch pivot arm 50 can move independently of the locking lever if movement of the locking lever is obstructed by the draw bar being in a rear position so that the upper end 58 of the locking lever cannot clear behind the draw bar depending leg 37. This is the situation that would occur when the oven is being used for conventional cooking and a suffrcient overheat occurs that the bimetal assembly pivots the pivot arm 50 but the locking lever cannot follow through the coupling of the spring 54 because the upper end of the locking lever is obstructed by the draw bar. In this case the pivot arm 50 will move and displace the leaf 53 sufficiently to open the safety switch contacts at the selected cooking overheat temperature.

However, if the door has been latched, so that the draw bar is pulled forwardly and the upper end 58 of the locking lever can clear the draw bar, the locking lever will follow the pivot arm through the spring coupling and the upper end 58 of the locking lever will move into an obstructing position behind the draw bar as the oven temperature reaches the selected temperature at which the door is to remain locked during a selfcleaning operation. In other words, the bimetals will have deflected sufficiently as the temperature in the oven rises above say 600F. (316C.) that the upper end of the lever 58 will have moved behind the draw bar. When the cleaning cycle has been concluded and oven temperatures are descending, the lever 58 will move out of an obstructing position at about the same temperature. The purpose of having the two bimetals, one being a thermal lag compensating bimetal, is explained in my U.S. Pat. No. 3,638,638.

The snap lever 38 attached to the draw bar moves forwardly with the draw bar. When so moved, the lever must effect positive and consistent recalibration of the safety switch 40 through the pivot arm assembly 39 while at the same time permitting a degree of overtravel by the draw bar. Additionally, the retaining force exerted upon the pivot arm asembly should not exceed a relatively low force to be compatible with the latching mechanism.

This is accomplished in accordance with my invention by providing a snap type lever 38 which may be likened to a toy snap cricket which will yield along the dash line 60 after the pivot arm assembly 39 (FIG. 7) has been moved to a position in which the calibrating screw 62 has bottomed against the wall of the lock box. Any further forward travel of the draw bar causes the snap-cricket lever 38 to break about the line 60. While the force required to occasion the break may be several pounds, only a fraction of a pound of force is required to maintaiin the break. Furthermore any additional forward travel of the draw bar does not result in any significant increase in the spring force exerted by the lever 38 upon the pivot assembly.

The lock box also includes a door latch indicator switch assembly 64 which includes a pair of switch leaves, one of which includes a portion extending in front of the depending leg 37 of the draw bar so that as the draw bar is moved forwardly the leaf contacts will meet to close the switch.

The draw bar is biased rearwardly by a torsion spring arrangement which includes an upper horizontal leg 68, a vertical leg 70 and a rearwardly projecting lever arm 72 which will shift the worm gear 74 to the left as indicated by the arrow for engagement with the gear 76. The worm gear 74 is driven by a timer 78 which is energized at the beginning of a cleaning cycle so that with the door latched and the two gears in engagement, the gear 76 will be driven in the direction indicated to open the timing switch 80 when the cleaning cycle is completed.

Referring to FIGS. 5 and 8, the channel structure 46 carrying the bimetals is secured to the main wall of the box 2 so as to be biased downwardly but yieldable in an upward direction to compensate for shifting of the oven liner relative to the wall upon which the box 2 is fastened, particularly during transportation of the range. The channel has a weakened neck portion 82 obtained by locating two holes as shown in FIG. 5 near the upstanding flange 84 which is riveted to the main wall of the box. As formed the channel structure has the upstanding flange 84 at an angle greater than a right angle, such as is best apparent in FIG. 8, so that in assembly the channel structure 46 is forced upwardly to rest on the top rear surface of the oven liner 10. The natural springiness of the sheet steel neck is sufficient to hold the distal end of the channel down against the oven liner.

As noted before the bimetals are isolated thermally from the channel 46 by a pair of ceramic spacers 47 (FIG. 8) and then a heat collecting angle plate 86 is fastened to the bimetals and channel along with the spacers. The angle plate promotes heat transfer from the top of the oven liner to the main bimetal 42.

The box 2 (FIG. 8) is secured to a vertical rear wall 88 of the range spaced rearwardly from the oven liner by a pair of fasteners 90 which pass through openings 92 adjacent the lower edge of the box 2 (FIG. 6). Tubular spacer sleeves 94 are interposed between the wall of the lock box 2 and the wall 88 of the range. The length of these spacer sleeves is selected in accordance with the particular range model and the selected attachment locations of the stabilizer bar and draw bar as explained previously. Since the box is secured to the range wall 88 only along its lower edge, the box is adapted to be titled slightly one way or another to compensate for manufacturing tolerances, without this affecting the operation of the components of the box or the latching and locking operation.

The circuit usable with the arrangement shown may be basically the same as that disclosed in US. Pat. No.

I claim:

1. In a cooking oven of the pyrolytic self-cleaning type for carrying out both cooking operations and cleaning operations, including an oven cavity defined by an oven liner;

heating means for said oven cavity;

a door for said oven cavity;

means for latching said door along its upper edge including a latching bolt movable into an aperture of a keeper plate; a bell crank pivotally mounted on said keeper plate.

said crank including one arm adapted to be moved sideways by said latching bolt to turn said crank, and another arm movable forwardly upon turning of said crank;

a locking and control mechanism box located generally at the upper rear of said oven liner, said locking mechanism including a draw bar movable forwardly to control switch means to permit initiation of self-cleaning cycle, said draw bar including a series of holes spaced apart in a front to rear direction;

said box including safety switch means operable to open in response to excessive oven temperatures;

said draw bar carrying lever means for operating said safety switch means from one position in which said safety switch means operates to an open position in response to an oven temperature in excess of safe cooking temperatures, to a second position in which said safety switch means operates to an open position in response to oven temperatures in excess of safe cleaning temperatures;

a linking bar connected at its forward end to said another arm of said crank, and having at its rear connecting means for engagement with said draw bar at one of said holes therein;

a stabilizer bar having its front end attached at the pivotal axis of said bell crank, and having a series of front to rear attachment locations, corresponding in front to rear spacing to the spacing of said holes of said draw bar; and

means for making a connection between a selected one of said stabilizer bar attachment locations with a fixed location on said box, and for making an attachment between said rear connecting means of said linking bar with a corresponding hole of said rear draw bar, the correspondence between the stabilizer bar attachment locations and said rear draw bar holes being successively forward stabilizer bar attachment locations corresponding to successively rearward draw bar holes.

2. In an oven according to claim 1 wherein:

said box includes bimetal means reflecting oven temperatures operable to move obstructing means into and out of a position obstructing movement of said draw bar when said draw bar is in a forward position, said bimetal means being carried in a structure projecting forwardly from said box to a location over said oven cavity, said projecting structure being biased into contacting relation with said oven cavity liner to compensate for shifting of said oven liner relative to said box.

3. In an oven according to claim 2 wherein:

means for attaching said box solely along its lower edge to permit tilting of said box to accommodate manufacturing tolerances.

4. In an oven according to claim 1 wherein:

said lever means is yieldable and of the snap-cricket type adapted to flex and then exert limited force upon movement beyond a predetermined point. 

1. In a cooking oven of the pyrolytic self-cleaning type for carrying out both cooking operations and cleaning operations, including an oven cavity defined by an oven liner; heating means for said oven cavity; a door for said oven cavity; means for latching said door along its upper edge including a latching bolt movable into an aperture of a keeper plate; a bell crank pivotally mounted on said keeper plate, said crank including one arm adapted to be moved sideways by said latching bolt to turn said crank, and another arm movable forwardly upon turning of said crank; a locking and control mechanism box located generally at the upper rear of said oven liner, said locking mechanism including a draw bar movable forwardly to control switch means to permit initiation of self-cleaning cycle, said draw bar including a series of holes spaced apart in a front to rear direction; said box including safety switch means operable to open in response to excessive oven temperatures; said draw bar carrying lever means for operating said safety switch means from one position in which said safety switch means operates to an open position in response to an oven temperature in excess of safe cooking temperatures, to a second position in which said safety switch means operates to an open position in response to oven temperatures in excess of safe cleaning temperatures; a linking bar connected at its forward end to said another arm of said crank, and having at its rear connecting means for engagement with said draw bar at one of said holes therein; a stabilizer bar having its front end attached at the pivotal axis of said bell crank, and having a series of front to rear attachment locations, corresponding in front to rear spacing to the spacing of said holes of said draw bar; and means for making a connection between a selected one of said stabilizer bar attachment locations with a fixed location on said box, and for making an attachment between said rear connecting means of said linking bar with a corresponding hole of said rear draw bar, the correspondence between the stabilizer bar attachment locations and said rear draw bar holes being successively forward stabilizer bar attachment locations corresponding to successively rearward draw bar holes.
 2. In an oven according to claim 1 wherein: said box includes bimetal means reflecting oven temperatures operable to move obstructing means into and out of a position obstructing movement of said draw bar when said draw bar is in a forward position, said bimetal means being carried in a structure projecting forwardly from said box to a location over said oven cavity, said projecting structure being biased into contacting relation with said oven cavity liner to compensate for shifting of said oven liner relative to said box.
 3. In an oven according to claim 2 wherein: means for attaching said box solely along its lower edge to permit tilting of said box to accommodate manufacturing tolerances.
 4. In an oven according to claim 1 wherein: said lever means is yieldable and of the snap-cricket type adapted to flex and then exert limited force upon movement beyond a predetermined point. 